Many other small mammals and birds also eat parts of it.
The seeds are dispersed when small mammals eat the fruits.
Sometimes, however, the mammals simply create a hole themselves and eat the pulp.
It is not known exactly which mammals eat the fruit, or what attracts them.
In fact, a past theory about the extinction of the dinosaurs was that newly evolving mammals ate all their eggs.
Or mammals of increasing size killed off the smaller reptiles and ate them.
Fish and marine mammals often eat synthetic materials, which then enters the food chain.
Butternuts are also important to wildlife: many mammals eat the nuts.
Most mammals eat this, as it is a good source of protein and other vital nutrients needed for caring for the young.
"I always thought the dinos faded out because mammals came along and ate their eggs," I said.